<?php
/**
 * Created by PhpStorm.
 * User: kd25
 * Date: 2016/11/16
 * Time: 10:55
 */
namespace util\invite;

class Code {
    //密码字典
    public $dic = array(
        0 => '0', 1 => '1', 2 => '2', 3 => '3', 4 => '4', 5 => '5', 6 => '6', 7 => '7', 8 => '8',
        9 => '9', 10 => 'A', 11 => 'B', 12 => 'C', 13 => 'D', 14 => 'E', 15 => 'F', 16 => 'G', 17 => 'H',
        18 => 'I', 19 => 'J', 20 => 'K', 21 => 'L', 22 => 'M', 23 => 'N', 24 => 'O', 25 => 'P', 26 => 'Q',
        27 => 'R', 28 => 'S', 29 => 'T', 30 => 'U', 31 => 'V', 32 => 'W', 33 => 'X', 34 => 'Y', 35 => 'Z'
    );

    public function encodeID($int, $format = 4)
    {
        $dics = $this->dic;
        $dnum = 36; //进制数
        $arr = array();
        $loop = true;
        while ($loop) {
            $arr[] = $dics[bcmod($int, $dnum)];
            $int = bcdiv($int, $dnum, 0);
            if ($int == '0') {
                $loop = false;
            }
        }
        if (count($arr) < $format)
            $arr = array_pad($arr, $format, $dics[0]);

        return implode('', array_reverse($arr));
    }

    public function decodeID($ids)
    {
        $ids = strtoupper($ids);
        $dics = $this->dic;
        $dnum = 36; //进制数
        //键值交换
        $dedic = array_flip($dics);
        //去零
        $id = ltrim($ids, $dics[0]);
        //反转
        $id = strrev($id);
        $v = 0;
        for ($i = 0, $j = strlen($id); $i < $j; $i++) {
            $v = bcadd(bcmul($dedic[$id{
            $i}], bcpow($dnum, $i, 0), 0), $v, 0);
        }
        return $v;
    } 
}